Framed biodegradable yarn structure and method

ABSTRACT

The techniques of this disclosure generally relate to a prosthesis including framed biodegradable yarn graft material having a frame and biodegradable yarns combined with the frame. The biodegradable yarns seal tissue integration openings within the frame. The frame provides long term mechanical strength while the biodegradable yarns provide acute strength and impermeability to prevent endoleaks. As the biodegradable yarns degrade, the drop in textile density creates tissue integration openings, through which tissue grows. The integrate of tissue into the framed biodegradable yarn graft material provides biological fixation of the prosthesis in vessels and prevents endoleaks and migration of the prosthesis.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/591,601, filed on Nov. 28, 2017, entitled “ADVANCED GRAFT MATERIALSFOR ENDOVASCULAR APPLICATIONS” of Borglin et al., which is incorporatedherein by reference in its entirety.

FIELD

The present technology is generally related to an intra-vascular deviceand method. More particularly, the present application relates to adevice for treatment of intra-vascular diseases.

BACKGROUND

A conventional stent-graft typically includes a radially expandablereinforcement structure, formed from a plurality of annular stent rings,and a cylindrically shaped layer of graft material defining a lumen towhich the stent rings are coupled. Stent-grafts are well known for usein tubular shaped human vessels.

To illustrate, endovascular aneurysmal exclusion is a method of using astent-graft to exclude pressurized fluid flow from the interior of ananeurysm, thereby reducing the risk of rupture of the aneurysm and theassociated invasive surgical intervention. The graft material oftraditional stent-grafts is extremely hydrophobic and presents a hostileenvironment for the recruitment and proliferation of cells. Theinability of tissue to integrate into the graft material prevents thebiological fixation of the stent-graft in vessels and makes thestent-graft susceptible to endoleaks and migration.

SUMMARY

The techniques of this disclosure generally relate to a prosthesisincluding framed biodegradable yarn graft material having a frame andbiodegradable yarns combined with the frame. The biodegradable yarnsseal tissue integration openings within the frame. The frame provideslong term mechanical strength while the biodegradable yarns provideacute strength and impermeability to prevent endoleaks. As thebiodegradable yarns degrade, the drop in textile density creates tissueintegration openings, through which tissue grows. The integrate oftissue into the framed biodegradable yarn graft material providesbiological fixation of the prosthesis in vessels and prevents endoleaksand migration of the prosthesis.

In one aspect, the present disclosure provides a frame and biodegradableyarns combined with the frame.

In another aspect, the disclosure provides a prosthesis including aproximal seal zone including a framed biodegradable yarn graft materialand an exclusion zone including permanent and impermeable graftmaterial.

In yet another aspect, the disclosure provides a method includingforming a prosthesis by forming a framed biodegradable yarn graftmaterial by combining biodegradable yarns with a frame.

The details of one or more aspects of the disclosure are set forth inthe accompanying drawings and the description below. Other features,objects, and advantages of the techniques described in this disclosurewill be apparent from the description and drawings, and from the claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a framed biodegradable yarn stent-graftin accordance with one embodiment.

FIG. 2 is an enlarged perspective view of a region II of the stent-graftof FIG. 1 in accordance with one embodiment.

FIG. 3 is a plan view of the region II of the stent-graft of FIG. 1 inaccordance with one embodiment.

FIG. 4 is a cross-sectional view of a graft material along the lineIV-IV of FIG. 3 upon initial deployment on a vessel wall in accordancewith one embodiment.

FIG. 5 is an enlarged plan view of the section of the graft material ofFIG. 3 after dissolution of biodegradable yarns in accordance with oneembodiment.

FIG. 6 is a cross-sectional view of the graft material along the lineVI-VI of FIG. 5 after a period of time after deployment on the vesselwall in accordance with one embodiment.

FIG. 7 is a cross-sectional view of a vessel assembly including thestent-graft of FIG. 1 after initial deployment within a vessel having adissection in accordance with one embodiment.

FIG. 8 is an enlarged cross-sectional view of a region VIII of thevessel assembly of FIG. 7 in accordance with one embodiment.

FIG. 9 is a cross-sectional view of the region VIII of the vesselassembly of FIG. 7 after a period of time after deployment of thestent-graft within the vessel in accordance with one embodiment.

FIG. 10 is a cross-sectional view of a vessel assembly including astent-graft in accordance with another embodiment.

DETAILED DESCRIPTION

FIG. 1 is a perspective view of a framed biodegradable yarn stent-graft100 in accordance with one embodiment. Referring now to FIG. 1,stent-graft 100, sometimes called a prosthesis, includes a framedbiodegradable yarn graft material 102 and one or more stent rings 104coupled to graft material 102. Illustratively, stent rings 104 areself-expanding stent rings, e.g., nickel titanium alloy (NiTi),sometimes called Nitinol, or self-expanding members. The inclusion ofstent rings 104 is optional and in one embodiment stent rings 104 arenot included. In another embodiment, stent rings 104 are balloonexpandable stents.

In accordance with this embodiment, graft material 102 includes aproximal opening 106 at a proximal end 108 of graft material 102 and adistal opening 110 at a distal end 112 of graft material 102.

Further, stent-graft 100 includes a longitudinal axis L. A lumen 114 isdefined by graft material 102, and generally by stent-graft 100. Lumen114 extends generally parallel to longitudinal axis L and betweenproximal opening 106 and distal opening 110 of stent-graft 100.

As used herein, the proximal end of a prosthesis such as stent-graft 100is the end closest to the heart via the path of blood flow whereas thedistal end is the end furthest away from the heart during deployment. Incontrast and of note, the distal end of the catheter is usuallyidentified to the end that is farthest from the operator/handle whilethe proximal end of the catheter is the end nearest the operator/handle.

For purposes of clarity of discussion, as used herein, the distal end ofthe catheter is the end that is farthest from the operator (the endfurthest from the handle) while the distal end of stent-graft 100 is theend nearest the operator (the end nearest the handle), i.e., the distalend of the catheter and the proximal end of stent-graft 100 are the endsfurthest from the handle while the proximal end of the catheter and thedistal end of stent-graft 100 are the ends nearest the handle. However,those of skill in the art will understand that depending upon the accesslocation, stent-graft 100 and the delivery system descriptions may beconsistent or opposite in actual usage.

Graft material 102 is cylindrical having a substantially uniformdiameter. However, in other embodiments, graft material 102 varies indiameter, is bifurcated at distal end 112, and/or is a multi-limbeddevice for branching applications. Graft material 102 includes an innersurface 116 and an opposite outer surface 118, e.g., cylindricalsurfaces in accordance with this embodiment.

FIG. 2 is an enlarged perspective view of the region II of stent-graft100 of FIG. 1 in accordance with one embodiment. FIG. 3 is a plan viewof the region II of stent-graft 100 of FIG. 1 in accordance with oneembodiment. Referring now to FIGS. 1, 2, and 3 together, graft material102 includes a frame 220 and biodegradable yarns 222.

In one embodiment, frame 220 is permanent, e.g., will last in the humanbody for an extended period of time such as 10 years or more. Frame 220is sometimes called non-absorbable, and persistent. In one embodiment,frame 220 is polyester terephthalate (PET), expanded polyesterterephthalate (ePET), nickel titanium alloy (NiTi), or other permanentgraft material or textile.

In contrast to frame 220, biodegradable yarns 222 are a biodegradablematerial, i.e., are biodegradable. As used herein, biodegradable meanscapable of being broken down in the human body, e.g., through contactwith fluid such as blood and/or tissue such as a vessel wall. Examplesof biodegradable yarns 222 include polymer polyglycolic-lactic acid(PLGA), poly(glycerol sebacate) (PGS), Polyglycolic acid (PGA), or PolyLactic Acid (PLA).

Frame 220 provides long term mechanical strength while biodegradableyarns 222 provide acute strength and impermeability to preventendoleaks. As discussed in further detail below, as biodegradable yarns222 degrade, the drop in textile density creates tissue integrationopenings, sometimes called ingress channels, through which tissue grows.

In accordance with this embodiment, frame 220 includes permanent yarns224. Biodegradable yarns 222 are combined with permanent yarns 224 andmore generally with frame 220 to form graft material 102. Generally,graft material 102 includes permanent yarns 224 and biodegradable yarns222 which are woven, knitted, sewn, or otherwise combined to creategraft material 102. In one embodiment, yarns are long string likemembers, sometimes called threads, fibers, filaments, or cylindricalstructures.

Biodegradable yarns 222 are illustrated as including a plurality ofvertical biodegradable yarns 222V and a plurality of horizontalbiodegradable yarns 222H. Similarly, permanent yarns 224 illustrated asincluding a plurality of vertical permanent yarns 224V and a pluralityof horizontal permanent yarns 224H. Yarns 222V, 222H, 224V, 224H areinterlaced with one another.

In accordance with this embodiment, each yarn 222, 224 is interlacedwith the other yarns 222, 224 in a weaving pattern, e.g., an over underpattern. For example, two adjacent horizontal permanent yarns 224H areinterlaced, e.g., in an over under or weaving pattern, with two adjacentvertical horizontal permanent yarns 224V in the view of FIGS. 2 and 3.This pattern is repeated to form frame 220.

Similarly, each biodegradable yarn 222 interlaced with frame 220 and theother biodegradable yarns 222 in a weaving pattern. In accordance withthis embodiment, there is a ratio of three biodegradable yarns 222 toeach permanent yarn 224, e.g., a 3/1 ratio. More generally, there aremore biodegradable yarns 222 than permanent yarns 224. In addition, adiameter D1 of biodegradable yarns 222 is less than a diameter D2 ofpermanent yarns 224.

However, depending upon the application, the size of yarns 222, 224 andthe weave pattern can be different than that illustrated in FIGS. 2-3.For example, the ratio of biodegradable yarns 222 to permanent yarns 224is more or less than 3/1 in other embodiments. Further, diameter D1 ofbiodegradable yarns 222 is equal to or greater than diameter D2 ofpermanent yarns 224 in other embodiments.

The illustrated arrangement of yarns 222, 224, e.g., woven, isillustrative only and in light of this disclosure those of skill in theart will understand that yarns 222, 224 can be combined in any one of anumber of different fashions to form graft material 102. For example,yarns 222, 224 are woven, knitted, sewn, or otherwise combined to creategraft material 102.

A tissue integration opening 226, e.g., a space, is defined by the twoadjacent horizontal permanent yarns 224H and the two adjacent verticalpermanent yarns 224V illustrated in FIGS. 2 and 3. More particularly,tissue integration opening 226 is defined by two adjacent verticalpermanent yarns 224V and two adjacent horizontal permanent yarns 224H.The other tissue integration openings 226 in graft material 102 aredefined in a similar manner.

Tissue integration openings 226 are sealed by biodegradable yarns 222.In accordance with the embodiment illustrated in FIGS. 2 and 3, tissueintegration openings 226 are sealed by three horizontal biodegradableyarns 222H interlaced with three vertical biodegradable yarns 222V.Generally, tissue integration openings 226 in frame 220 are sealed bybiodegradable yarns 222.

As tissue integration openings 226 are sealed by biodegradable yarns222, graft material 102 is essentially impermeable. In one embodiment,there are small pores 228, sometimes called interstices 228, betweenyarns 222, 224. Pores 228 are typically formed due to the overlappingnature of yarns 222, 224 and the inability to make yarns 222, 224completely flush with one another along the entire length of yarns 222,224. However, pores 228 are sufficiently small that fluid leakagethrough pores 228 is negligible. Although pores 228 are illustrated, inother embodiments, graft material 102 has an absence of pores and iscompletely impermeable.

Over time, biodegradable yarns 222 biodegrade and dissolve. This removesbiodegradable yarns 222 from tissue integration openings 226 of frame220, sometimes called opens tissue integration openings 226. Onceopened, tissue integration openings 226 provide ingress channels ingraft material 102 to encourage tissue integration therein. An exampleof the dissolution of biodegradable yarns 222 and tissue integrationinto tissue integration openings 226 is set forth below in reference toFIGS. 3-6.

FIG. 4 is a cross-sectional view of graft material 102 along the lineIV-IV of FIG. 3 upon initial deployment on a vessel wall 402 inaccordance with one embodiment.

Referring now of FIGS. 1, 3 and 4 together, stent-graft 100 is deployedwithin a vessel including the vessel wall 402. For example, stent-graft100 is deployed to treat an abdominal aortic aneurysm, a thoracic aorticaneurysm, a dissection, or other medical condition.

Upon initial deployment, biodegradable yarns 222 remain in theiroriginal form and are undissolved. As discussed above, prior todissolution of biodegradable yarns 222, graft material 102 isessentially impermeable. This, in turn, minimizes and essentiallyeliminates leaks through graft material 102, e.g., type IV endoleaks.

Paying particular attention to FIGS. 1 and 4 together, stent-graft 100contacts vessel wall 402. Accordingly, fluid flows though stent-graft100, i.e., through lumen 114. Due to the impermeability of stent-graft100, vessel wall 402 including any defect associated therewith, e.g., adissection or aneurysm, are excluding from the pressurized fluid flowthrough stent-graft 100.

FIG. 5 is an enlarged plan view of the section of graft material 102 ofFIG. 3 after dissolution of biodegradable yarns 222 in accordance withone embodiment. FIG. 6 is a cross-sectional view of graft material 102along the line VI-VI of FIG. 5 after a period of time after deploymenton vessel wall 402 in accordance with one embodiment.

Referring now of FIGS. 1, 5-6 together, after a period of time,biodegradable yarns 222 (see FIGS. 3-4) dissolve. However, frame 220including permanent yarns 224 remain in the same configuration as wheninitially deployed or approximately there so.

Biodegradable yarns 222 slowly dissolve over a period of time. Asbiodegradable yarns 222 dissolve, tissue integration openings 226 areuncovered by biodegradable yarns 222 and opened.

Over time, biodegradable yarns 222 are replaced with tissue 604 fromvessel wall 402 that integrates within and through tissue integrationopenings 226 as illustrated in FIG. 6. Tissue 604 encases frame 220including permanent yarns 224 and fills tissue integration openings 226preventing leakage through tissue integration openings 226 in accordancewith this embodiment. The integrate of tissue 604 into graft material102 provides biological fixation of stent-graft 100 in vessels andprevents endoleaks and migration of stent-graft 100. Generally,stent-graft 100 becomes integrated with the vessel including vessel wall402.

As discussed below in reference to FIGS. 7-10, stent-graft 100 is usedto cover and treat various defects in a vessel.

FIG. 7 is a cross-sectional view of a vessel assembly 700 includingstent-graft 100 of FIG. 1 after initial deployment within a vessel 702having a dissection in accordance with one embodiment. FIG. 8 is anenlarged cross-sectional view of a region VIII of vessel assembly 700 ofFIG. 7 in accordance with one embodiment. In FIG. 7, stent-ring 104 isnot illustrated for simplicity.

Referring to FIGS. 1, 7-8 together, a dissection is a condition in whichan inner layer 706 of vessel 702 tears to have a dissection opening 708.Fluid, e.g., blood, flows through dissection opening 708 and into afalse lumen 710 between inner layer 706 and one or more other outerlayers 712 of vessel 702. Left untreated, false lumen 710 can ruptureouter layers 712 of vessel 702 leading to serious complications andoften death.

In accordance with this embodiment, stent-graft 100 is deployed to coverand exclude dissection opening 708. As discussed above, when initiallydeployed, stent-graft 100 is impermeable thus sealing dissection opening708 and preventing pressurized fluid flow through false lumen 710.

FIG. 9 is a cross-sectional view of region VIII of vessel assembly 700of FIG. 7 after a period of time after deployment of stent-graft 100within vessel 702 in accordance with one embodiment. Referring now toFIGS. 1, 7-9, due to the covering and exclusion of the dissection withstent-graft 100, dissection opening 708 heals and closes and false lumen710 collapses. At the same time, biodegradable yarns 222 dissolveallowing tissue 904 integration into tissue integration openings 226 ofstent-graft 100 including between permanent yarns 224 of frame 220.

FIG. 10 is a cross-sectional view of a vessel assembly 1002 including astent-graft 1000 in accordance with another embodiment. Stent-graft 1000of FIG. 10 is similar to stent-graft 100 of FIG. 1 and only thesignificant differences are discussed below. Stent-graft 1000 isillustrated with an absence of stent-rings 104 for simplicity butincludes stent-rings 104 in other embodiments.

In accordance with this embodiment, a graft material 1001 and moregenerally stent-graft 1000 includes at least three zones 1004, 1006,1008 in accordance with this embodiment. Proximal seal zone 1004 extendsfrom proximal end 108 to exclusion zone 1006. Exclusion zone 1006extends from proximal seal zone 1004 to distal seal zone 1008. Distalseal zone 1008 extends from exclusion zone 1006 to distal end 112.

Proximal seal zone 1004 and distal seal zone 1008 include framedbiodegradable yarn graft material 102 similar to that discussed. Moreparticularly, only proximal seal zone 1004 and distal seal zone 1008include framed biodegradable yarn graft material 102 having frame 220and biodegradable yarns 222.

However, exclusion zone 1006 is formed of non-biodegradable material, ispermanent, and impermeable. For example, in accordance with variousembodiments, exclusion zone 1006 is graft material made of polyesterterephthalate (PET), ePET, or other similar graft material or textile.

Stent-graft 1000 is deployed into a vessel 1010 to exclude an aneurysm1012 using any one of a number of techniques well known to those ofskill in the art. More particularly, proximal seal zone 1004 and distalseal zone 1008 are deployed proximally and distally to aneurysm 1012,respectively.

Proximal seal zone 1004 and distal seal zone 1008 directly contact avessel wall 1014 of vessel 1010. Over time, biodegradable yarns 222 ofproximal seal zone 1004 and distal seal zone 1008 dissolve. This allowstissue integration into proximal seal zone 1004 and distal seal zone1008 of stent-graft 1000 in a manner similar to that discussed above.This, in turn, prevents leakage around proximal seal zone 1004 anddistal seal zone 1008 and migration of stent-graft 1000.

Further, exclusion zone 1006 is deployed over aneurysm 1012, i.e., toexclude aneurysm 1012. Accordingly, blood flows through exclusion zone1006 and more generally through stent-graft 1000 thus excluding aneurysm1012. As exclusion zone 1006 may not contact vessel wall 1014 but spananeurysm 1012, exclusion zone 1006 does not include biodegradablematerial such that tissue integration openings 226, e.g., see tissueintegration openings 226 of FIGS. 5-6, are not created in stent-graft1000 in exclusion zone 1006.

It should be understood that various aspects disclosed herein may becombined in different combinations than the combinations specificallypresented in the description and accompanying drawings. It should alsobe understood that, depending on the example, certain acts or events ofany of the processes or methods described herein may be performed in adifferent sequence, may be added, merged, or left out altogether (e.g.,all described acts or events may not be necessary to carry out thetechniques). In addition, while certain aspects of this disclosure aredescribed as being performed by a single module or unit for purposes ofclarity, it should be understood that the techniques of this disclosuremay be performed by a combination of units or modules associated with,for example, a medical device.

In one or more examples, the described techniques may be implemented inhardware, software, firmware, or any combination thereof. If implementedin software, the functions may be stored as one or more instructions orcode on a computer-readable medium and executed by a hardware-basedprocessing unit. Computer-readable media may include non-transitorycomputer-readable media, which corresponds to a tangible medium such asdata storage media (e.g., RAM, ROM, EEPROM, flash memory, or any othermedium that can be used to store desired program code in the form ofinstructions or data structures and that can be accessed by a computer).

Instructions may be executed by one or more processors, such as one ormore digital signal processors (DSPs), general purpose microprocessors,application specific integrated circuits (ASICs), field programmablelogic arrays (FPGAs), or other equivalent integrated or discrete logiccircuitry. Accordingly, the term “processor” as used herein may refer toany of the foregoing structure or any other physical structure suitablefor implementation of the described techniques. Also, the techniquescould be fully implemented in one or more circuits or logic elements.

What is claimed is:
 1. A prosthesis comprising: a frame; and biodegradable yarns combined with the frame.
 2. The prosthesis of claim 1 where the frame comprises permanent yarns.
 3. The prosthesis of claim 2 wherein a diameter of the permanent yarns is greater than a diameter of the biodegradable yarns.
 4. The prosthesis of claim 2 wherein there are more biodegradable yarns than permanent yarns.
 5. The prosthesis of claim 1 wherein the frame comprises tissue integration openings.
 6. The prosthesis of claim 5 wherein the tissue integration openings are sealed by the biodegradable yarns.
 7. The prosthesis of claim 5 wherein each of the tissue integration openings are defined by two adjacent vertical permanent yarns of the frame and two adjacent horizontal permanent yarns of the frame.
 8. The prosthesis of claim 1 wherein the frame and the biodegradable yarns are woven together.
 9. The prosthesis of claim 1 further comprising a framed biodegradable yarn graft material comprising the frame and the biodegradable yarns.
 10. The prosthesis of claim 9 further comprising at least one stent ring coupled to the framed biodegradable yarn graft material.
 11. A prosthesis comprising: a proximal seal zone comprising a framed biodegradable yarn graft material; and an exclusion zone comprising permanent and impermeable graft material.
 12. The prosthesis of claim 11 further comprising: a distal seal zone comprising the framed biodegradable yarn graft material.
 13. The prosthesis of claim 12 wherein the exclusion zone extends from the proximal seal zone to the distal seal zone.
 14. The prosthesis of claim 11 wherein the framed biodegradable yarn graft material comprises permanent yarns combined with biodegradable yarns.
 15. The prosthesis of claim 14 wherein the permanent yarns are woven with the biodegradable yarns.
 16. A method comprising: forming a prosthesis comprising: forming a framed biodegradable yarn graft material by combining biodegradable yarns with a frame.
 17. The method of claim 16 further comprising sealing tissue integration openings within the frame with the biodegradable yarns.
 18. The method of claim 17 further comprising deploying the prosthesis within a vessel, wherein the framed biodegradable yarn graft material contacts a vessel wall of the vessel.
 19. The method of claim 18 wherein the biodegradable yarns biodegrade opening the tissue integration openings.
 20. The method of claim 19 wherein tissue from the vessel wall fills the tissue integration openings and encases the frame. 